Composite hydrogels filled with rhamnolipid-based nanoemulsion, nanostructured lipid carrier, or solid lipid nanoparticle: A comparative study on gel properties and the delivery of lutein

Abstract

Rhamnolipid-stabilized nanoemulsion (NE)/nanostructured lipid carrier (NLC)/solid lipid nanoparticle (SLN) was incorporated into κ-carrageenan/konjac glucomannan (KC-KGM) composite hydrogel to explore the effect of lipid composition on properties and lutein delivery performances of filled hydrogels (FH). The viscosity and crystallinity of emulsified lipids increased with the elevation of solid lipid content. Rheology and texture profile analysis suggested that solidified lipid particles led to greater modulus, hardness, and chewiness in FH. The creep-recovery test confirmed NLC-FH had the shortest retardation time and the highest recovery rate. NLC-FH also exhibited better stress attenuation capacity and lower stress relaxation, verifying that the filling of NLC improved the viscoelasticity of FH more effectively. When exposed to UV light, the inclusion of EGCG in NE/NLC/SLN-FH prolonged the half-life of lutein from 2.05 to 13.91, 19.28, and 33.02 h respectively. Lutein remained the most stable when embedded in NLC-FH with the addition of EGCG as its half-life extended by 11 times during storage. During in vitro digestion, FH retarded the release of lutein in the early digestion phase (mouth & stomach), whereas EGCG enhanced the release of lutein during intestinal digestion and the bioaccessibility of lutein was shown to be the highest in NE-FH (29.67%), followed by NLC-FH (28.22%) and SLN-FH (23.37%). These findings expanded the application of rhamnolipid-stabilized lipids in hybrid gel systems for property improvement and the delivery of lipophilic compounds.